The present invention relates to a hand-operable and portable pencil sharpener for use by tradespeople such as carpenters for sharpening a carpenter""s pencil.
In the prior art, the most important of which is exemplified by U.S. Pat. No. 6,092,293, there is described a carpenter""s pencil sharpener of the type as described in the present application. A disadvantage of that specific pencil sharpener is that the blade, which is secured next to the slot, whereby to cut an exposed point on the pencil lead, is curved and, accordingly, the material of the blade is constantly under stress and can break during use, rendering the device inoperable. Another disadvantage is that the centering collar is snap-fitted within a resilient track disposed inwardly in a base enclosure whereby to allow rotation of the collar relative to the base about a central axis. Once the collar is fitted within the resilient track, it is not removable therefrom and, if any debris or dust enters the resilient track, it can cause the centering collar to jam, rendering the sharpener unusable. A still further major disadvantage of the sharpeners is that they do not sharpen the extremity of the lead to a fine point, as the lead is of rectangular cross-section. When the pencil is rotated, shavings of the wood about the pointed end and both side edge portions of the lead only are cut. This leaves the extremity of the lead blunt and in most cases the pencil cannot inscribe fine lines, which is important when inscribing certain marks on material pieces to be cut or machined.
It is a feature of the present invention is provide a hand-operable and portable pencil sharpener which substantially overcomes the above-mentioned disadvantages of the prior art.
According to the above feature, from a broad aspect, the present invention provides a hand-operable and portable pencil sharpener which comprises a housing having a conical cavity therein. The cavity is of circular cross-section and defines an open inlet end tapering to a narrow inner end. A collar is provided about the open inlet end and formed integral with the housing, and defines a circular cavity concentric with the open inlet end. A pencil centering insert is provided in close rotational fit within the circular cavity and rotatable therein. The pencil centering insert has a pencil centering slot. Removable attachment means is provided for retaining the pencil centering insert in the circular cavity. A longitudinal through slot is provided along a side wall of the conical cavity. A flat straight blade having a sharp longitudinal edge is secured adjacent to the longitudinal through slot, with the sharp longitudinal edge projecting into the cavity whereby to shave a portion of the extremity of a pencil rotated in the conical cavity and centered by the centering slot of the pencil centering insert.
According to a still further broad aspect of the present invention, there is provided a pencil lead abrading element secured to the housing to abrade a fine point on the free end of a lead of a pencil.